Nicholas, > > To confirm, when you enable buffered FILEIO, your able to reach > comparable results with Samba, right..? > I got much closer to my Samba results, yes. > If your able to switch backends and reach 1 Gb/sec performance, that > would tend to indicate that it's something specific to the backend, and > not an iscsi fabric specific issue. > >> The NAS I am comparing against, which is performing surprisingly well, >> is also set up to use iblock. > > Please share what NAS and the version of LIO that it's using for > comparison. (eg: cat /sys/kernel/config/target/version) > The Commerical NAS I have to compare against is a Synology DS1511+. It has a hardware configuration that is quite close the the system I am working on. The version string: Target Engine Core ConfigFS Infrastructure v3.4.0 on Linux/x86_64 on 3.2.30 The version I am running: Target Engine Core ConfigFS Infrastructure v4.1.0-rc-m1 on Linux/x86_64 on 3.2.0-4-amd64 > It depends on a number of things. One is the physical queue depth for > each of the drives in the software raid. Typical low end HBAs only > support queue_depth=1, which certainly has an effect on performance. > This value is located at /sys/class/scsi_device/$HCTL/device_queue_depth > > Another factor can be if the individual drives in the raid have the > underlying WriteCacheEnable bit set. This can be checked with 'sdparm > --get=WCE /dev/SDX', and set with 'sdparm --set=WCE /dev/sdX'. > > Also, you'll want to understand the implications of using this, which is > that in case of a power failure there is no assurance the data in the > individual drive's cache has been written out to disk. > I confirmed WCE is set on all disks in the raid array. I also turned on NCQ, setting queue_depth to 31. It made a small improvement (about 5%). > Since you've already eliminated a different default_cmdsn_depth value, > it's likely not going to be a iscsi-target issue. It's most likely an > issue of one of the software RAID configurations being faster for non > buffered IO. > The best test I have to look at this would be to do a dd direct to the volume, to the raid array, and directly to the disks and compare those values to the copy from the windows system. I'll give that a shot tomorrow. Scott -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
